 | Bob Crager of Lewis Street Glass is a 26 year veteran in the glass business. Lewis Street Glass is a leading Wichita Glass company, serving the entire Wichita/Sedgwick County area since 1919. They do anything and everything having to do with glass, both residential and commercial. They also do Auto glass. They are located at 743 South Market, facing Kellogg on the South, and you can reach them by phone at (316) 263-8259. You can email Bob Crager at bcrager@lewisstreetglass.com |
Glass
2012-11-19 10:26:20
Should we replace our old windows to sell our home?
A- It’s hard to give you a meaningful answer to your question without having taken a look at your windows and see what we’re dealing with. But, as a general rule, whether you're replacing windows in an older house, or choosing windows for a new house, your decisions on what type of windows to buy will be among the most important decisions you will make in terms of energy use. Because of the impact windows have on both heat losses in the winter, and heat gains in the summertime, proper selection of window products can be troubling for most folks.
To add to the confusion, window glazing technology has changed tremendously in recent years. The best window glazings today insulate nearly four times better than the best commonly available windows from just twenty years ago. Window technology has improved very dramatically in recent years, and the net result is the lowering of your energy bills. And that could be a big deal for most folks. High efficiency windows are a gift that keeps on giving.
Let's discuss some of the most important energy features of windows that are used in both replacement windows, and new construction today. Until the 1980s the primary way manufacturers improved the energy performance of windows was to add additional layers of glazing, or panes. Double glazing insulates almost twice as well as single glazing. Adding a third or fourth layer of glazing results in even further improvements. Some of these windows use glass only, but others use thin plastic films for the inner glazing layers. With double-glazed windows the air space between the panes of glass has a big effect on overall energy performance. A very thin air space does not insulate as well as a thicker air space because of the conductivity through that small space. Many window manufacturers have increased the thickness of the air space in their double-glazed windows from ¼" to ½" or more. If the air space is too wide, however, convection loops between the layers of glazing can occur. Beyond about 1", you don't get any further gain in energy performance by virtue of thicker air spaces. It's a point of diminishing returns to try to go thicker than about an inch of air space. By substituting a denser, lower conductivity gas such as argon for the air in a sealed insulated glass window, heat loss can be reduced significantly. Most major window manufacturers offer argon-gas fill as an option in their most popular windows. Other gases that have been or are being used in windows include carbon dioxide, krypton, and argon-krypton mixtures. Tinted glass and tinted window films have long been used in commercial buildings to reduce heat gain through windows. Improved, lightly tinted windows are becoming more common for the residential market in southern (cooling-dominated) climates. These newly implemented glazings can reduce the solar heat gain, without reducing visibility as much as the older tinted glass and films. More than any other single improvement, the invention and commercial development of low-emissivity (low-e) coatings in the 1980s really revolutionized window technology. Thin, transparent coatings of silver or tin oxide permit visible light to pass through, but they effectively reflect infrared heat radiation back into the room. This reduces heat loss through the windows in the wintertime. A variety of low-e windows are now available for different climate zones and different applications in any particular location. Low-e windows with high solar heat gain coefficients are appropriate for northern climates, where passive solar heating is advantageous, while "southern low-e" windows with low heat gain coefficients are appropriate in milder climates where summer cooling is more significant than winter heating.
The edge spacer is what holds the panes of glass apart and provides the airtight seal in an insulated glass window. Traditionally, these have been hollow aluminum channels, usually filled with desiccant beads. Aluminum has extremely high conductivity. That didn't matter when the glazing did not insulate very well, but as better performing glazings were developed, proportionately more heat was lost through the edges. Since about 1990, a number of improved edge spacers have come onto the market. Some are made of thin-walled steel and have a thermal break. Others are made of silicone foam or butyl rubber. Generally, better edge seals are a low-cost option when changing out windows, and well worth considering. Interesting, huh?
So…in summation, we believe that most savvy buyers today will pay particular attention to the windows in any home they’re thinking about buying, and if yours are either new or in very like-new condition, this could be an important consideration to any buyer thinking about buying your existing home. Pointing them out to a potential buyer is a great way to justify your asking price in most cases, and most buyers are aware that great windows will result in lower energy bills and more comfortable living, than in a home where the windows are a question mark. We hope this is helpful in answering your questions, both on your existing home, and your new one. More next month...
